This invention relates to adhesive tapes or sheets for medical use and processes for the production thereof, and more particularly to adhesive tapes or sheets containing nitroglycerin in the adhesives which is used for medical treatment for and/or prevention against angina pectoris, myocardial infarction paroxysm and cardiac insufficiently, and processes for the production of such tapes or sheets.
Among internal treatments for ischemic heart disease is vasodilator therapy, and wherein nitroglycerin is used as coronary vasodilator. It is known that nitroglycerin has effects such as dilating of the coronary artery, releasing contracture of the coronary artery and further dilating collateral vessils and resistance vessels, consequently increasing oxygen supply to the ischemic area of cardiac muscle. And also it is known that nitroglycerin has effects such as dilating arteries and reducing the blood pressure throughout the body which leads to reduction of the load being applied to the heart, and at the same time, dilating veins and reducing the amount of venous return which leads to reduction of the forward-load to the heart, and consequently the oxygen consumption in the cardiac muscle is reduced.
Due to the above mentioned effects, nitroglycerin is used for the treatment for heart diseases such as myocardial infarction or angina pectoris.
Conventionally, nitroglycerin was administered by intravenous injection, in the form of sublingual tablets or ointment, and the effect lasting time of each was respectively a few minutes, 20 to 30 minutes, or 3 to 5 hours.
For the treatment for paroxysm from angina pectoris, usually the sublingual tablet containing nitroglycerin is used, but the effect lasting time is short.
When there is necessity to keep up the medical effect of nitroglycerin for long time, for example, in case of the treatment for cardiac insufficiency or the prevention of angina pectoris, an ointment containing nitroglycerin is used. When nitroglycerin is administered in the form of ointment, the ointment prepared by dispersing 2% of nitroglycerin lactose into lanoline-vaseline basis and contained in a tube is generally used. An administering amount of this ointment is determined as follows. At first approximately 1.25 cm of the ointment is pushed out onto a scaled parchment paper applicator (6.times.9 cm), then applied onto the frontal chest skin and the amount of the ointment is increased by approximately 1.25 cm in each successive time until a headache occurs which is a symptom of side-effect. If this side-effect occurs then the amount of the ointment is decreased. An amount satisfying the purpose of medical treatment and just less than the occurrence of a headache-side-effect, it is considered as the maximum permissible amount or a proper administering amount. In actual use, the ointment is to be pushed out onto a scaled parchment paper in an amount not exceeding that fixed according to the above mentioned manner (generally 2.5 to 5 cm length, the amount of the ointment approximately 0.7 to 1.5 g, the amount of nitroglycerin approximately 14 to 30 mg), and said amount of ointment is to be applied onto the frontal chest skin (the area to be applied onto is usually considered to be 200 cm.sup.2 or more). In order to avoid the evaporation of nitroglycerin and to prevent the ointment from staining clothes, the ointment-applied part of the body is to be covered with plastic film (e.g. polyvinyliden chloride film which is commercially available under the trade name of "Saran Wrap") which is to be fixed by adhesive tapes. In order to remove the applied ointment, it is necessary to wash with a lukewarm aqueous solution of soap or remove it by gauze containing alcohol. As mentioned above, the use of ointment is troublesome, and it is very difficult to determine an exact amount to be used accurately. Further, as other ways of administering nitroglycerin, there were suggested the ways such that micro capsules or absorbent mediums carrying nitroglycerin therein are dispersed into adhesives or combined with cataplasm or plaster. However, the above mentioned administering ways are not practical. Since there is required a step of putting nitroglycerin into capsules or a step of forming absorbent mediums, the preparation process is troublesome. And according to usual production process of cataplasm or plaster, there is a danger that nitroglycerin explodes.
Recently, a plaster containing nitroglycerin was published (Japanese Patent Laid-Open No. 2604/1980). However, in this adhesive plaster is not improved to obtain suitable retention and release of nitroglycerin.